A KOHLER toilet and pedestal sink set against a dark green wall

The secret to toilet efficiency.

Less water + smaller valve = big flush.

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The story of the KOHLER® Highline® 1.0 gallon per flush toilet began more than 10 years ago. It's a story of small tweaks, discoveries and design changes that led to a high-performing toilet that uses just one gallon per flush.

The original design featured a large flush valve and a base with a fast flow rate. This created a quick flush, something that reassured consumers, according to Dan Halloran, Senior Principal Engineer. It required greater plug resistance, a larger hole and a long channel for the water to travel through, not to mention more water per flush.

Our engineers sought to achieve the same powerful flush with less water.

"We discovered that the area immediately after the flush valve was the key to reducing water use," Dan said. "The secret to toilet efficiency was that small piece of real estate within the channel."

They found that re-engineering the canister to send water through a smaller valve with more pressure achieved a more complete flush with less water.

"We've found ways to direct water more precisely," Dan continued. "And this research into increased efficiency is inspiring the designs we're working on right now—two to three generations ahead of the product being released."


Your Kohler story begins here.